9810 Getting Close - Parts Question (Photos)


Well, I'm getting close to having two fully functional 9810s, out of the 4 that I have.

I have one that works great and using board swapping, I have a 2nd one working (almost), except for a single board.

I'm going to try replacing the standard 74 series parts today and see if I can get lucky. But there are several parts that I suspect might be custom HP parts.

Anyone have any idea what the parts (M1, M2, X1, X2, X3), shown in the photo, are?

I will probably be getting rid of the other two units as "for parts" units.




perhaps it can be helpful to ask this guy:

Best regards



Your suggestion led me to:


I have crossed and verified all but the 1820-0367. On another board, it is marked 1820-1594. But neither part shows up in this cross reference.

My luck is running good so maybe that part will not be bad. There are also 3 parts of this type. I have 3 such bad boards. Surely, I can find 3 good ones out of 9 parts, as a last resort.




I took a look at other board types and found the 1820-1594 part on a known good working board. It had 4 parts.

Then, I took a look at another identical board and found that it had the 1820-1594 in four places. On the board that I am trying to fix, only 3 such parts are shown. In the 4th position the part is marked SN7495. So, it looks like the M2 part may be a 7495 part.


I have a fairly long list of HP 1820- numbers :-) ( No, it's not machine readable, so don't ask for it to be e-mailed). Anyway.
1820-0367 = SN7495AN and 1820-1594 = SN5495AN (which is just a 'better' version of the 7495A)


As you see in the post right above yours, that is the part that I suspected it was.

I'm going to just buy all the parts and replace them one at a time. Only 20 parts. I should have a 2nd working unit this weekend.



Hello Mike,

I pulled this board from my 9810, and the parts You
called M1 are SN7495N from TI, and the X1 is a 74121,
as You wrote. All other parts are the same, only production
date some weeks different. The 73xx numbers are the production week.


I check this site and found all but the 1820-0367 part.


But it has 7400 for M1 and you had it as a 7495 (shift register)???

Turns out that not all my boards are marked with the same part numbers M1 is a 7400 on another board. It also cross-checs on this site. Maybe you were looking at the wrong part.

But unfortunately M2 is still not shown. On my other board it is a 1820-1594. So, it is showing up as a different HP part.

Maybe I'll get lucky and the M2 part will not be bad.




You are right, the M2 part is the 7495. Sorry for the confision.

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